This statement describes something that could have happened but did not. Yahweh did help him, so he was not lying in the place of silence. Alternate translation: "If Yahweh had not been my help ... silence (See: [[rc://en/ta/man/translate/figs-hypo]])
The abstract noun "help" can be expressed as a verb. Alternate translation: "If Yahweh had not helped me" (See: [[rc://en/ta/man/translate/figs-abstractnouns]])
Here "would be lying down" refers to "death" and "in the place of silence" refers to the grave." Alternate translation: "in a short time, I would be dead, lying in a silent grave" (See: [[rc://en/ta/man/translate/figs-euphemism]])